One example of a device which does provide an indication of when an aerosol container has been emptied is provided by U.S. Pat. No. 4,063,664 to Meetze, Jr., which utilizes a counter and/or a sensor to determine evacuation of an aerosol container. In a system like that of Meetze, Jr., Muderlak and Maloney, in U.S. Pat. No. 4,830,791, make use of a timer which provides pulses at periodic intervals, a counter which counts the pulses and generates a latch signal after a predetermined number of pulses is counted (corresponding to the calculated lifetime of the odor control cartridge) and a signal activated by the latch signal. As is apparent, this Muderlak and Maloney approach cannot compensate for variations in frequency and intensity, since the device discussed operates using a predetermined "count" of pulses which are generated at a predetermined frequency, to provide the desired signal.
In a refinement on their earlier work, Muderlak and Maloney describe a system very similar to that of Meetze, Jr. whereby the number of actuations of an aerosol dispenser is counted, and an indication of the dispenser being empty is provided after 3072 actuations, in U.S. Pat. No. 5,038,972. In U.S. Pat. No. 5,126,078, Steiner, Holzner, Harunan and Owen disclose a system which uses a timer to indicate either the need for replacement of the cartridge acting as the source of material to be dispensed or replacement of the battery (which are designed to coincide) of a fan type dispenser.
A unique approach to calculating the dispensing of a predetermined amount of a material is disclosed by Dial, Chang and Huang in U.S. Pat. No. 5,772,074. In their patent, Dial et al. teach a method wherein a dispensing score representative of the time of operation of a dispenser multiplied by a factor representative of the frequency or intensity of dispensing is calculated and the calculated dispensing score is compared with a predetermined total score. Although describing a system not heretofore seen, the Dial et al. patent does not disclose a programmable dispenser in accordance with the present invention.
Unfortunately, nothing in the prior art provides a system having the flexibility to provide variations in time of operation, including start and stop times as well as days of operation and frequency and/or intensity of dispensing, whether in a fan-driven dispenser or a discrete event aerosol or pump dispenser. Moreover, nothing seen provides such a programmable dispenser which provides status indicators for characteristics such as refill and/or battery life, nor a remote programmer/status check device. The present invention provides such a system.